Description

When using Zend_Cache_Backend_TwoLevels and the memcached backend, calls to getFillingPercentage is done.
If using multiple memcached servers and one memcached server is down, the getFillingPercentage throws an exception.
This renders the whole caching mechanism dead...
It should still work as long as some memcached servers are up. The filling percentage stats isn't that important for the functionality.

I propose to just ignore any memcached servers that are down in this call.